The Kidney Transplant Histocompatibility Study aims at the evaluation of the efficacy of histocompatibility typing (serologically defined HL-A antigens) and donor-recipient matching on the rate of success of renal transplants. Reproducible typing results will be maintained by using standardized NIH typing trays, standardized techniques, quality control workshops, and the storage of donor and recipient lymphocytes for retyping in the event of rejection problems or upon the availability of newer typing sera able to further discriminate antigens. Patient and donor records will be meticulously kept on standard data forms for submission to the central office for monitoring and analysis.